Hosts are pressured to 'respond' to booking requests within 24 hours, and that means either approving or declining the request, not just replying to any questions. Many hosts confuse an enquiry with a request, because they are given options of 'pre-approve' or 'decline', and assume that they must select one of these to stop the clock ticking on their response rate. If it had been established in correspondence that the listing was unsuitable then I can understand the host choosing 'decline' rather than 'pre-approve'. And I can believe that she was told by Airbnb that she had to select one of these options even though it was only an enquiry, because I was told the same thing!